Mobile and portable radio products have utilized a variety of switch mechanisms to control certain radio functions, such as volume control, on-off, and channel selection. Conventional switch mechanisms include electro-mechanical switches, rotary resistive elements, and/or mechanically encoded rotary switches. Unfortunately, many of the electromechanical types of switches have limited reliability due to contact wear and contact contamination as well as problems associated with poor synchronization between electrical contact and tactile feedback. The rotary type switches have proven to be only marginally reliable and often require interconnection to the internal radio circuitry via expensive flex circuits and connectors.
Accordingly, there is a need for an improved frequency domain switch apparatus for use in radio products.